Refining vessel draw-off system



Dec. 1, 1953 A. SAWYER REFINING VESSEL DRAW-OFF SYSTEM Filed Feb. 191951 CZLtorl L. Saw-get Cinvarzbor' rM Qbboraegs Patented Dec. 1, 1953UNITED sTArs-s rarest OFFICE REFINING VESSEL DRAW-OFF SYSTEM Alton L.Sawyer, Morristown,.N. J. Application Februaryi19, 1951, SerialNo.211,685

1 Claim. (CL 210-51 This invention deals with the increasing of yieldsin the refining of fatty oils by use of a multi-tube draw-on system.More specifically, it.

relates to a liquid phase indicating system for the drawing off oflayers after multi-layer settling in therefining of fatty oils.

During the refining of fatty oils such as cottonseed oil, soy bean oil,and the like, the oil is run into a vertical tank and the reagents suchas caustic soda and water are fed into the top. lhe mixture is thenagitated for a certain length of time under specified temperature andpressure conditions, and allowed to settle. In the settling operation,the heavier aqueous soap stock falls to the bottom of the tank as aseparate layer. There is generally an emulsion layer floating on thissoap stock layer, composed of particles of refined oil and soap stock.Disposed above the emulsion layer is the refined oil layer.

In conventional drawing-off operations, it is necessary to draw off thesoap stock layer and the emulsion layer. If some of the emulsion is leftbehind, it reduces the quality of the refined oil. However, if theemulsion layer is drawn ofi completely and some oil layer is also drawnofi, the yield of refined oil is obviously reduced. In conventionalpractice, th tendency is to maintain good refined oil quality and, toinsure complete removal of the emulsion layer, some of the refined oillayer is also drawn OK and wasted.

Attempts have been made to reduce this wastage of refined oil by use ofsight glasses in the draw-off line at the bottom of the settling tank.However, such glasses usually become coated with emulsion layer, so thatby the time this layer is cleared oii by the flowing liquid, anappreciable loss of refined oil results. Also, even if the difference inphases is observed at the proper time, there is still loss of refinedoil incurred by the time the draw-ofi line valve is completely closed.

An object of the present invention is to enable visual and otherexamination of the fiowing mass within the tank to determine thedownward progress of the various phases therein. Another object is toenable detection of the upper phase change of the emulsion layer insufficient time to allow for shutting cit of the draw-off line valvebefore any wastage of refined oil takes place. Other objects will becomeapparent from the description which follows. lhese objects are attainedby inserting into the bottom of the tank two small bleed lines, one or"which penetrates the liquid in the bottom of the tank while the otherdraws ofi liquid at the very bottom of the tank.

The invention will be more clearly understood by reference to thedrawing in which Figure 1 shows a vertical cross sectional View of aportion of the settling tank, while Figure 2 is a similar view of thebottom portion of the tank showing a different arrangement for the bleedlines. Similar numerals refer to similar parts in the various figures.

Referring again to the drawing, numeral l represents a vertical tankhaving lower tapered portion 16 terminating with flanged collar 2 towhich disk head 3 is bolted. Outlet or drawoff line l is inserted intohead 3 to enable drawing off of contents in tank l. Valve 5 is providedin draw-01f line 4 for throttling and shutoiT purposes. In tank I(Figure I) may be observed the lower soap stock layer 8, theintermediate emulsion layer i and upper refined oil layer 6.

As shown in Figure 1, tube 42 is inserted through head 3 to enabledrawing off the contents from the very bottom of tank I. Also, insertedthrough conical portion It of tank 1 is line 9, the upper end 10 ofwhich extends into the liquid in the conical portion of the tank nearthe center thereof. Both lines l2 and 9 are provided with shut-01fvalves l3 and H respectively. End E0 of tube 9 is disposed far enoughwithin tank I to enable one, when valve 5 is completely open, emptyingtank 5, to close valve 5 in sufficient time to prevent refined oil 5from being discharged therethrough.

lhis control is accomplished by opening valves H and 13 when valve 5 isopened to discharge the contents of tank I. As the contents aredischarged through discharge line 6, small streams are simultaneouslydischarged through lines a and i2. These small streams enable theoperator to sample and inspect, as well as smell and feel the materialflowing past their intake points. Thus, for example, when emulsion lreaches inlet iii of tube 9 in Figure 1, it will be immediatelytransferred through tube 9, so that the operator sampling the dischargeat the outlet of tube 9 will immediately detect that the emulsion isentering the conical section of tank 5. Since end it is placed farenough in tank 5, the operator can then proceed to throttle valve 5 andbe ready to shut off the fiow completely as soon as the refined oilphase 8 begins to discharge out of bleed line !2, thereby preventing anyloss of valuable refined oil.

Figure 1 shows one modification of the placement of bleed tubes 9 and52. Another modification is depicted in Figure 2. In this case, tube 9'is installed in head 3 of the tank, while tube l2 is mounted in thelower portion of collar 2. Although these locations in Figures 1 and 2are preferred, there is no particular limitation as to the manner inwhich the tubes 9 and #2 are mounted as long as tube 8 or 9' has itsupper end ID extending into the liquid drained far enough to give theoperator sufficient time to close valve without losing valuable refinedoil. It is also required that the tank connection of line [2 or I2 be asclose to the bottom of tank I as possible. It is apparent from thedrawing that the outlets of lines 9 and 12 may be drained ofi to thesoap stock tank or any other suitable container.

In actual practice, draw-off line 4 is usually about 4" pipe, more orless, while lines 9 and 12 are A" pipe. If the diameter of line 9 is toosmall, the flow therethrough may be too slow due to the high viscosityof the fluids transferred. Conversely, if the diameter is too large, itmay be necessary to throttle valve II which would then cause a physicalchange to take place in the case of the emulsion due to the orificeefiect which breaks the emulsion.

It is preferable to insert upper end IU of line 9 into above about to ofthe volume of the soapstock originally present to insure a time lagduring discharge sufficient to close valve 5 without discharge ofrefined oil. Also, end III of pipe 9 should be far enough away from theinner wall of tank I to avoid catching therein any film or otherundesirable material which may be sliding down the side of the vessel.Numeral l4 represents a conventional sight glass which is normally usedand which has been mentioned previously herein.

The apparatus of the present invention also allows the operator to drawout, with accuracy, only the soapstock, thus enabling him to treat theemulsion by heat or chemicals to recover additional oil, without thecomplicating presence of the emulsifiable soapstock. Although soapstockis mentioned here as the bottom layer, it could also consist of washwater, clean water or the like.

I claim:

A process for discharging, with minimum oil loss, some of the contentsfrom the bottom of a tank provided with a discharge valve and used in.settling fatty oils which had been treated with a heaver aqueous liquid,said contents being composed of a bottom aqueous layer, a supernatanttop oil layer, and a supernatant intermediate emulsion layer of oil andaqueous liquid, comprising, while discharging said contents, the step ofdrawing a first substantially continuous bleed sample from within theliquid disposed in the bottom of the tank until a supernatant layer isobserved, then closing the discharge valve gradually, drawing a secondsubstantially continuous bleed sample from the bottom of the tank, andclosing the discharge valve completely when the supernatant layer isobserved in the second bleed sample, said first bleed sample being drawnfrom the liquid at a point separated vertically from the point ofdrawing of said second bleed sample by a volume equal to at least aboutone-fifth to onefourth of the volume of the bottom aqueous layeroriginally present therein, thereby allowing sufiicient time for closingthe discharge valve within the time interval when the supernatant layeris first observe-:1 at the two bleed lines.

ALTON L. SAWYER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 725,363 Powter Apr. 14, 1903 864,153 De Lany Aug. 27, 19571,245,366 Mathesius Nov. 6, 1937 1,803,083 Wack Apr. 28, 1931

